It has been known for some time that 1-deamino-8-D-arginine-vasopressin, commonly known as desmopressin, has a useful biological effect for the treatment of diabetes insipidus, presents antidiuretic activity and reduces and normalizes the prolonged bleeding time.
Desmopressin has been administered as a drug by different routes, in different presentation forms and in combination with different excipients. By way of example, the administration of desmopressin by nasal, oral, vaginal, rectal, subcutaneous, intravenous and intramuscular route has been described. Oral administration route with gastrointestinal absorption of desmopressin has the problem that the bioavailability is clearly lower than by other administration routes, since desmopressin is degraded by stomach and intestinal enzymes and is metabolized in the liver. The most common alternative administration route of desmopressin, in the form of its acetic salt, is through nasal or oral mucosa, given the convenience of administration through these routes compared to other parenteral administration routes.
Nasal pharmaceutical compositions of desmopressin acetate in the form of drops or spray in which the active substance is absorbed through the mucous membrane are known in the state of the art. For example, document EP 0710122 A1 describes aqueous compositions of desmopressin for nasal administration by means of a spray, stable at room temperature and which compositions contain a buffer, an osmotic pressure-controlling agent and a quaternary amine as a preservative, particularly benzalkonium chloride. An aqueous composition comprising parabens at a concentration of 1 mg/ml as preservatives instead of quaternary amines is also described in the examples.
Document WO 2004/014411 A1 relates to an aqueous composition for nasal administration in the form of drops or spray comprising desmopressin and tris(hydroxymethyl)aminomethane as stabilizer and absorbent. In particular this composition can contain auxiliary agents such as methyl and/or propyl p-hydroxybenzoate.
Likewise, document WO 03/97080 A1 describes an aqueous nasal composition of desmopressin stable at room temperature and in an acceptable support furthermore comprising a pH buffer, a paraben as a preservative and a cosolvent improving the preservative properties of parabens.
Furthermore, document WO 94/03157 A1 relates to a composition for nasal or vaginal administration in the form of liposome dispersion or microemulsion made up of salmon calcitonin, although desmopressin is also cited, and a thermosetting polymer. This composition also contains methylparaben as a preservative.
Documents WO 01/60394 A1 and WO 2004/019910 A2 describe pharmaceutical compositions of desmopressin which are administered orally or nasally by means of spray and which are absorbed through the mucous membrane. In particular, document WO 01/60394 A1 describes an oral, nasal or sublingual composition of desmopressin with malic acid as a buffer of pH 4-6, and at the same time as a preservative, which can additionally contain other preservatives, such as parabens for example. This composition also necessarily contains an osmotic agent and is administered, according to the examples, by means of a nasal or sublingual spray, or syrup. Furthermore, document WO 2004/019910 A2 describes a buccal spray for the administration of active substances through the oral mucosa, in which desmopressin is mentioned as one of the possible antidiuretic active substances.
Document EP 0381345 A1 describes a pharmaceutical composition in aqueous solution form comprising desmopressin and carboxymethyl cellulose and which is administered intranasally in the form of drops or with a sprayer or by means of intramuscular, intravenous or subcutaneous injection.
Likewise, document WO 2005/115339 A2 describes liquid, semi-solid or solid pharmaceutical compositions with a component which increases the absorption of the drug through the oral, nasal, gastrointestinal or vaginal mucosa. In particular, a liquid composition comprising desmopressin as a drug and methylparaben as a preservative and administered through the nasal mucosa, or by gastrointestinal, oral, ocular or vaginal route, is described.
Other oral pharmaceutical compositions of desmopressin in solid dose form are also known in the state of the art. Documents EP 0163723 A1, EP 0689452 A1, EP 752877 A1, EP 1473029 A1, EP 1500390 A1, EP1501534 A1, EP 0517211 A1, WO 2005/089724 A1 and WO 2005/046707 A1 describe different oral compositions in the form of tablets, capsules or powders comprising desmopressin and which compositions are absorbed through the oral mucosa and/or gastrointestinally. However, all these solid formulations have limited dose versatility and are complex to administer for populations having difficulty swallowing.
Finally, buccal patches containing desmopressin are additionally known. Document U.S. Pat. No. 5,298,256 A describes a pharmaceutical composition containing desmopressin in the form of a buccal patch adhered to the oral mucosa.
The previously cited documents describe compositions of desmopressin which are administered through the oral or sublingual mucosa by means of patches, capsules, tablets or syrups and through the nasal mucosa by means of drops or sprays. However, the nasal administration route presents irritation problems due to osmotic agents of the composition and/or the agents used to increase the absorption, and problems derived from the small area available for the absorption in the nasal cavity. In contrast, oral administration forms known in the state of the art have the drawback of being impersonal, i.e., they have scarce or null flexible-dose which allows treating each patient in an individualized manner, a problem that will be aggravated if, as is the case of desmopressin, the pharmacological activity of the drug is high. In addition, the solid formulations for oral administration of desmopressin of the state of the art are complex to administer for special populations such as the elderly with difficulty in swallowing and for children who do not want to do it.
Therefore, there is still a need to find a presentation form that jointly solves the problems of irritation and capacity of the absorption area presented by the nasal route, and furthermore the lack of flexible-dose and the difficulty of administering for special populations which oral administration forms present. A stable, liquid, flexible-dose pharmaceutical composition for oral administration containing neither osmotic agents nor absorption enhancing agents and comprising a therapeutically effective amount of desmopressin is object of the present invention.
A problem of drugs with peptides, particularly those having sulfur bridges such as desmopressin, is the easy degradation of their aqueous solutions, therefore the presence of preservatives in these solutions is necessary. Among the preservatives known in the state of the art for aqueous compositions of the oxytocin peptide families are parabens or p-hydroxybenzoates.
In addition to the previously mentioned documents which describe compositions containing parabens, document US 2004/0235956 A1 describes liquid compositions of carbetocin for their administration to mucosae in the form of solutions, syrups, suspensions or elixirs. In a particular embodiment the liquid solution of carbetocin comprises parabens as preservatives.